1. Field of the Invention
The present invention relates to an image pickup system, and more particularly to an image pickup system that obtains an image of an object using a CMOS image sensor.
2. Description of the Related Art
Various techniques have been conventionally proposed for preferably picking up an image of an object using a CMOS image sensor (hereinafter, also referred to as a CMOS image pickup device).
Specifically, Japanese Patent Application Laid-Open Publication No. 2009-136447, for example, discloses an endoscope system configured to cause a light source to carry out pulse light emission in a predetermined period (non-readout period) within a period for one field determined by a field signal supplied to a CMOS image pickup device and cause the light source to stop pulse light emission in a period (readout period) other than the predetermined period within the period for one field. In other words, the Japanese Patent Application Laid-Open Publication No. 2009-136447 discloses a method for suppressing brightness unevenness of an image picked up with the CMOS image pickup device by controlling the light emission state of the light source while operating the CMOS image pickup device by using another method different from the common rolling-shutter method which does not include a non-readout period.